Multi-carier configuration, activation and scheduling

ABSTRACT

Embodiments of block acknowledgements request apparatus, systems, and methods are generally described herein. Other embodiments may be described and claimed. An aggregated block of a plurality of data frames is received from an originator transmission, with each data frame including a medium access control (MAC) header. An acknowledgement policy that is solicited by the originator is identified in a quality of service field in at least one of the MAC headers of the received transmission. A single block acknowledgement is transmitted to the originator acknowledging receipt of one or more of the plurality of data frames in the aggregated block of data frames.

CLAIM OF PRIORITY

This is a continuation of U.S. patent application Ser. No. 11/167,491filed on Jun. 27, 2005, which is herein incorporated by reference in itsentirety.

BACKGROUND

The inventive subject matter pertains to communication systems and, moreparticularly, to wireless transmission and reception of data in acommunication system.

In modern communication systems, data typically is sent in packet formfrom one communication node through a network to another communicationnode. These packets typically include one or more headers and a payload,which is the useful data to be sent, received and used by thecommunication nodes. Such data transmissions in a Media Access Control(MAC) protocol may take place at a relatively low transmission rate.

During transmit and receive operations, handshaking occurs toacknowledge the proper receipt of transmitted data. An acknowledgementis typically requested by a transmitting node after sending a block ofdata. If errors occur, an error acknowledgement is returned to thetransmitting node, and the data is transmitted.

Often the acknowledgement request must be repeated. The acknowledgementrequest may be repeated in subsequent physical layer protocols, therebyfurther lowering the overall transmission rate.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a communication system in accordance withvarious embodiments of the present invention.

FIG. 2 is a layout of a media access control protocol header depictingvarious embodiments for implementing a block acknowledgement request.

FIG. 3 is a table layout of an indicator of the media access controlprotocol header depicting various embodiments of the present invention.

FIG. 4 is a layout of a multiple-frame data block in accordance withvarious embodiments of the present invention.

FIG. 5 is a flowchart of various transmission methods for blockacknowledgement control in accordance with various embodiments of thepresent invention.

FIG. 6 is a flowchart of various reception methods for blockacknowledgement control in accordance with various embodiments of thepresent invention.

DETAILED DESCRIPTION

FIG. 1 is a block diagram of a communication system 100 in accordancewith various embodiments of the present invention. The communicationsystem 100 has a wireless transmitter 10. The wireless transmitter 10 iscoupled to an analog-to-digital/digital-to-analog converter (ADC) and atransmitter/receiver (Tx/Rx) 11. The ADC & Tx/Rx 11 converts signalsfrom digital to analog in the transmit direction and from analog todigital in the receive direction of wireless transmitter 10. Wirelesstransmitter 10 is also coupled to a processor 13. Processor 13 controlsoperation of transmitter 10.

ADC & Tx/Rx 11 is coupled to an antenna 12. Antenna 12 may be adirectional or omni-directional antenna, including, for example and notby way of limitation, a dipole antenna, a monopole antenna, a patchantenna, a loop antenna, a microstrip antenna, or various other types ofantennas suitable for transmission and/or reception of data signals. Insome embodiments, the wireless transmitter may have multiple antennas.

The communication system 100 also has a wireless receiver 20. Wirelessreceiver 20 is coupled to an analog-to-digital/digital-to-analogconverter (ADC) and transmitter/receiver (Tx/Rx) 21. ADC & Tx/Rx 21converts signals from digital to analog in the transmit direction andfrom analog to digital in the receive direction of wireless receiver 20.Wireless receiver 20 is also coupled to processor 23. Processor 23controls operation of receiver 20.

ADC &Tx/Rx 21 is coupled to an antenna 22. Antenna 22 may be adirectional or omni-directional antenna, including, for example and notby way of limitation, a dipole antenna, a monopole antenna, a patchantenna, a loop antenna, a microstrip antenna, or various other types ofantennas suitable for transmission and/or reception of data signals. Insome embodiments, the wireless receiver 20 may have multiple antennas.

Wireless network 30 couples the transmitter 10 to the receiver 20 forthe transfer of data. The roles of the transmitter 10 and the receiver20 may be reversed, in that the transmitter 10 may receive and thereceiver 20 may transmit data. Wireless network 30 may be a singlewireless network in one embodiment, or in other embodiments wirelessnetwork 30 may be any combination of wireless and wireline networks.Wireless network 30 may in other embodiments comprise a wireless localarea network (WLAN), wireless personal area network (WPAN) and/orwireless metropolitan area network (WMAN).

Communication system 100 of FIG. 1 may be one in which the Standards ofthe Institute of Electrical and Electronic Engineering (IEEE), Standards802.11, published in 1998 together with subsequent amendments apply. TheIEEE 802.11 Standard currently provides a definition for media accesscontrol (MAC) headers and services. In 2003, an IEEE 802.11 Task Group n(TGn) was created. TGn's objective is to define modifications to thePhysical Layer (PHY) and MAC layer to deliver a throughput of at least100 megabits per second. The IEEE 802.11n Standards are currently at theproposal stage. Several proposals exist. A further objective of the802.11n Standards is to be downward-compatible with Standards 802.11a/b/g.

Previous standards, such as the draft IEEE 802.11e standard, call for ahandshaking arrangement between transmitter and receiver. In thisarrangement, a block of data frames is sent, but each individual dataframe is sent as a separate transmission. Each data frame has it'sacknowledge (ack) policy set to “1, 1,” indicating block acknowledgement(BA). Next, the originator sends a separate block acknowledgementrequest (BAR) frame to solicit a BA response. The recipient then, inturn, responds with a (BA) frame.

The transmitter may also choose to solicit a normal acknowledgement foran individual data frame. This is achieved by setting the ack policy onan individual data frame to “0, 0” which will cause the recipient torespond with a normal ack (acknowledge) frame.

With the high data rate desired for IEEE Standard 802.11n, scope existsfor improving the efficiency of this exchange. One key enhancement isthe aggregation of multiple data frames into a single transmission. Whendoing this, the conventional acknowledgement mechanism described may bemodified to improve efficiency further.

In an embodiment of the invention, wireless transmitter may performnon-aggregate or aggregate transmissions. In an aggregate transmission,wireless transmitter 10 aggregates one or more data frames into a blockthat is then sent as a single transmission. An aggregate transmission issignaled either implicitly by the nature of the transmission orexplicitly with a signaling field at the head of the transmission.

If a block acknowledgement is required for the aggregated data, then thewireless transmitter 10 will set the ack policy in each data frame inthe aggregate transmission to “0, 0” (normal ack policy).

If the wireless transmitter 10 chooses to solicit the blockacknowledgement using a conventional BAR frame (either in the sametransmission or a subsequent transmission), then each data frame in theaggregate transmission will have its ack policy set or flag to “1, 1”(block ack policy).

The use of normal ack policy thus has a new meaning: when used in a dataframe in a non-aggregate transmission, the normal ACK policy solicits anACK frame from the recipient. When set in one or more data frames in anaggregate transmission, the normal ACK policy solicits a BA frame fromthe recipient

The aggregate transmission is sent from transmitter 10, through ADC&Tx/Rx 11, through antenna 12, through wireless network 30, throughantenna 22, through ADC &Tx/Rx 21 to wireless receiver 20.

Wireless receiver 20 receives the aggregate transmission, identifies itas an aggregate transmission and parses it to extract the individualdata frames. One or more of the data frames may not be received due totransmission errors. If the ACK policy of one or more of thesuccessfully received data frames is set to “0, 0” (normalacknowledgment), then receiver 20 sends a BA to transmitter 10.Otherwise, the conventional acknowledgement policy as defined in thecurrent IEEE 802.11 Standard is followed.

Thus, a field in the header of the data frames making up an aggregatetransmission is used to request a BA, rather than the transmitter 10transmitting a separate BAR frame. The BAR may still be used, as needed,for sequence number synchronization and for flushing a reorder bufferwhen data frames are discarded by the transmitter 10. Soliciting a BAusing a field in the header of each data frame, making up an aggregatedmay improve reliability over sending a separate BAR frame, especially ifthat BAR frame is aggregate with the data in the same transmission,since the solicitation is repeated in each data frame. Elimination ofthe BAR may also remove ambiguity when no BA response is received. No BAresponse will be received if either none of the data frames werereceived or the response transmission was not detected by theoriginator. Because the latter is far less likely (signal detection isfar more robust than demodulation), full retransmit can be doneimmediately rather than resending a BAR, receiving a BA, and thenretransmitting the full aggregated block.

When the BA is received by the transmitter 10, the identity of properlyreceived frames is included in the BA. If any errors occur, only framesof the block that were not acknowledged are re-transmitted bytransmitter 10. If the block acknowledgement is not received bytransmitter 10, then all frames of the multiple-frame block requirere-transmission.

FIG. 2 is a layout 200 of a media access control protocol header 201depicting various embodiments for implementing a BAR. The media accesscontrol (MAC) header 201 is concatenated with the frame body 205. In anembodiment, the frame body 205 may include from zero to several thousandoctets of data. An octet is 8 bits or a byte.

The BA solicitation is signaled in the Quality of Service (QoS) Controlfield 203. For example, the QoS Control field 203 is may be two octetsin length. The specific settings for the BA solicitation will beexplained infra.

FIG. 3 is a table layout 300 of ack policy field in the QoS Controlfield of the media access control protocol header depicting variousembodiments of the present invention. Bits 301 and 302 of the Ack(Acknowledge) Policy field 203 (refer to FIG. 2) indicate the policy foracknowledgement or other handshaking between the transmitter 10 (FIG. 1)and the receiver 20. Bits 301 and 302 are referred to as bits 5 and 6for block acknowledgement modes.

Bits 5 and 6 for values of: 0, 1 indicate no BA requested; 1, 0 indicateno explicit BA requested; and 1, 1 indicate BA requested after eachblock.

When the values 303 and 304 of bits 301 and 302 respectively are 0, 0 asshown in FIG. 3, two meanings are possible for this configuration. Thefirst meaning is to return a BA, if the frame was received in anon-aggregate transmission.

The second meaning 305 of the policy for handshaking indicates that ifan aggregate transmission was received, a BA is to be returned to theoriginator immediately following the aggregate transmission.

So for various embodiments of the present invention, the second meaning305 controls the handshaking policy in an aggregate, multiple-frametransmission. Therefore, only one BA is sent for the entire transmissionof multiple frames of data. This BA is sent in response to the BAsolicitation signaled in the header 201 (e.g. in the QoS Control field203, FIG. 2) of each data frame. A separate BAR need not be sentfollowing transmission of the block of frames. This may improve thetransmission efficiency.

FIG. 4 is a layout of a multiple-frame data block in accordance withvarious embodiments of the present invention. A multiple-frame datablock 400 may have N data frames generally shown as 401, 402, and 403.Although FIG. 4 depicts three data frames, the multiple-frame data block400 may include additional or fewer data frames.

In an embodiment, bits 5 and 6 (301, 302 of FIG. 3) of the MAC header ofeach data frame are set to 0, 0. As a result, when the N data frames401-403 are received by a receiver, only one BA is returned to theoriginator for the entire multiple-frame data block 400. Therebyconsiderable savings may be obtained over returning a BA to theoriginator after each data frame by the elimination of all BA messagesand BARs, except the last one. In addition, no separate BAR needs to besent by the originator following transmission of the multiple-frame datablock 400, which may potentially improve the transmission efficiency.

FIG. 5 is a flowchart of various transmission methods 500 for blockacknowledgement control in accordance with various embodiments of thepresent invention. The transmit behavior flow may begin at block 501.Block 501 comprises waiting until one or more frames of data are readyfor transmission by transmitter 10. Multiple frames are aggregated intoa single multiple-frame data block for transmission. This data block 400is shown in FIG. 4.

In block 503, a determination is made whether a block acknowledgementrequest (BAR) is required for the data transmission. If a traditionalBAR is required (e.g. for sequence number synchronization), block 503transfers control to block 505 via the YES path. In block 505, bits 5, 6(301, 302) of the ACK policy are set to 1, 1 in each data frame, and aBAR is appended to the data frames for transmission. Control istransferred to block 509.

In various embodiments of the present invention, no BAR is required, andblock 503 transfers control to block 507 via the NO path. Bits 5, 6(301, 302) of the ACK policy are set to 0, 0 in each data frame. Controlis then transferred to block 509.

Block 509 transmits the multiple frames of data as a single aggregatedata block with the appropriate acknowledgement policy in each MACheader. Block 511 then waits for BA to be received. If a BA is notreceived, block 511 transfers control to block 513 via the NO path.Block 513 re-transmits all data frames to the receiver. Then the methodis ended.

If the BA is received, as is typically the case, block 511 transferscontrol to block 515 via the YES path. Block 515 may then retransmit anydata frames that the BA indicated were received with an error, whileeliminating from retransmission any properly received data frames. Themethod is then ended.

FIG. 6 is a flowchart of various reception methods for blockacknowledgement control in accordance with various embodiments 600 ofthe present invention. The receive behavior flow may begin at block 602.Block 602 determines whether a receiver (e.g. the receiver 20) receiveddata frame transmission with aggregated frames of data from atransmitter (e.g. the transmitter 10). If not, the block 602 transferscontrol via the NO path to block 606. Block 606 handles the datareception and acknowledgement in a suitable, non-aggregate, conventionalmanner. The method is then ended.

If the receiver 20 received an aggregate transmission, block 602transfers control to block 604 via the YES path. Block 604 thendetermines whether the data frames have been received with the ACKpolicy bits 5 and 6 set to 0, 0. If not, block 604 transfers control toblock 606 via the NO path. Block 606 handles the data reception in asuitable, non-aggregate, conventional manner. The method is then ended.

If the ACK policy bit were set to 0, 0, block 604 transfers control toblock 608 via the YES path. Block 608 prepares a single blockacknowledgement, BA, for transmission to the transmitter 10. The BA mayidentify which data frames were received without error by the receiver20. Then, the BA is transmitted to the transmitter 10. The method isthen ended.

It should be noted that the methods described herein do not have to beexecuted in the order described, or in any particular order. Moreover,various activities described with respect to the methods identifiedherein can be executed in parallel fashion. It will be understood thatalthough “Start” and “End” blocks are shown, the methods may beperformed continuously.

The Abstract is provided to comply with 37 C.F.R. §1.72(b) requiring anAbstract that will allow the reader to ascertain the nature of thetechnical disclosure. It is submitted with the understanding that itwill not be used to interpret or limit the scope or meaning of theclaims.

In the foregoing Detailed Description, various features are occasionallygrouped together in a single embodiment for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed embodiments of the subjectmatter require more features than are expressly recited in each claim.Rather, as the following claims reflect, inventive subject matter liesin less than all features of a single disclosed embodiment. Thus thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separate preferred embodiment.Individual claims may encompass multiple embodiments of the inventivesubject matter.

Although some embodiments of the invention have been illustrated, andthose forms described in detail, it will be readily apparent to thoseskilled in the art that various modifications may be made thereinwithout departing from the spirit of these embodiments or from the scopeof the appended claims. Although some embodiments of the invention havebeen illustrated, and those forms described in detail, it will bereadily apparent to those skilled in the art that various modificationsmay be made therein without departing from the spirit of theseembodiments or from the scope of the appended claims.

What is claimed is:
 1. A method of communicating in a wireless localarea network, the method comprising: receiving a first transmission froman originator in the wireless local area network, the first transmissioncomprising a single transmission having an aggregated block of aplurality of data frames each data frame including a medium accesscontrol (MAC) header, wherein the first transmission does not include aseparate block acknowledgement request (BlockAckReq) frame; identifyingan acknowledgement policy solicited by the originator in a quality ofservice (QoS) field as a BlockAck policy or a Normal acknowledgementpolicy in at least one of the MAC headers of the received firsttransmission; and transmitting a single block acknowledgement (BlockAck)to the originator acknowledging receipt of one or more of the pluralityof data frames in the aggregated block of data frames.
 2. The method ofclaim 1 further comprising identifying in the BlockAck which of theplurality of data frames in the received first transmission werereceived without error.
 3. The method of claim 1 further comprising:receiving a second transmission from the originator including a repeatof only those of the plurality of data frames in the aggregated block ofthe first transmission, if any, which were not correctly received in thefirst transmission.
 4. The method of claim 1 further comprising:determining that the received first transmission is a transmission withthe aggregated block of the plurality of data frames and not aconventional transmission having a single data frame.
 5. A wirelesscommunication device comprising: a receiver configured to receive anddemodulate a first wireless transmission from an originator, the firstwireless transmission comprising a single transmission including anaggregated block of a plurality of data frames, with each data frameincluding a respective medium access control (MAC) header; a processorcoupled to the receiver to identify an acknowledgement policy solicitedby the originator in a quality of service (QoS) field as a BlockAckpolicy or a Normal acknowledgement policy in at least one of the MACheaders of the received transmission and to prepare a blockacknowledgment (BlockAck) message acknowledging receipt of the pluralityof data frames of the aggregated block in a single frame; and atransmitter coupled to the processor to modulate and transmit the blockacknowledgement to the originator.
 6. The device of claim 5 wherein thereceiver and transmitter are configured to receive and transmitutilizing protocols in conformance with an Institute of Electrical andElectronics Engineers (IEEE) 802.11n standard.
 7. The device of claim 5wherein the receiver includes multiple antennas.